Permanent deformation of keratin-containing fibers is usually carried out in such a way that the fiber is mechanically deformed, and the deformation is fixed using suitable aids. Before and/or after this deformation, the fiber is treated with a keratin-reducing preparation. After a rinsing operation, the fiber is then treated with an oxidizing agent preparation in the so-called fixing step, rinsed, and the deformation aids (curlers, papillotes) are removed during or after the fixing step. When a mercaptan, for example ammonium thioglycolate, is used as the keratin-reducing component, the mercaptan cleaves a portion of the disulfide bridges of the keratin molecule to form thiol groups, resulting in softening of the keratin fiber or swelling of the fibers, with enlargement of the fiber diameter. During the subsequent oxidative fixing, disulfide bridges are re-linked in the keratin of the hair, so that the keratin structure is fixed in the specified deformation. Alternatively, it is known to use sulfite instead of the mercaptans for the hair deformation. By use of hydrogen sulfite solutions and/or sulfite solutions and/or disulfite solutions, disulfide bridges of the keratin are cleaved in a sulfitolysis process according to the equationR—S—S—R+HSO3(−)→R—SH+R—S—SO3(−),thus achieving softening of the keratin fiber. Reducing agents including hydrogen sulfite, sulfite, or disulfite do not have the strong inherent odor of the mercaptan-containing agents. The cleavage, as described above, may be reversed in a fixing step, using an oxidizing agent, to form new disulfide bridges.
When dyeing of the keratinic fiber in addition to the shaping is also desired, the dyeing may be carried out as a separate treatment before or after the shaping that takes place. However, in particular in the case of oxidative dyeing, this results in extreme stress on the keratinic fibers, since each oxidative treatment of the fibers damages their internal structure. In addition, such an operation is very time-consuming, since a period of two weeks or more must be provided between the shaping and the dyeing treatment in order to avoid the above-described extreme stress and accompanying damage. For this reason, several methods for simultaneously shaping and dyeing keratinic fibers, in particular hair, have already been proposed. In many cases, for this purpose an oxidizing agent preparation that includes substantive dyes and/or oxidation dye precursors in addition to the oxidizing agent is used in the fixing step. Such a procedure is described in DE 19713698 C1, for example. However, this procedure has the disadvantage that the dyeing takes place at the same time as the fixing, i.e., at a time when the fibers to be treated are placed on deformation aids and are thus under mechanical tension. This hinders the uniform application of the dye, so that there is a risk of a nonuniform dyeing result.
Methods for simultaneously shaping and dyeing of hair are known from EP 0352375 A1 and EP 1287812 A2, in which a keratin-reducing preparation that already includes the necessary substantive dyes and/or oxidation dye precursors is used. At least a portion of the particular keratin-reducing preparation is applied to the hair after it has been mechanically deformed. However, the substantive dyes and/or oxidation dye precursors used for the dyeing do not always have satisfactory stability with respect to the keratin-reducing preparation, so that nonuniform shaping and dyeing results may occur in the event that the substantive dyes and/or oxidation dye precursors react with the keratin-reducing preparation.
It is therefore desirable to provide a method for shaping and dyeing keratinic fibers, in particular human hair, in which the shaping and the dyeing may be carried out in a single process, and which gives a comparable or better shaping result, uniformly dyes the keratinic fibers in the desired tint, and results in little or even no damage to the hair. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with this background of the invention.